Manufacturing apparatus for hydraulic cement composition and manufacturing method for hydraulic cement composition

Abstract

To make it possible to continuously produce a hydraulic cement composition, employing an acidic material and a basic material as raw materials, wherein CO2 released from energy necessary in manufacturing and CO2 discharged from the raw materials are reduced.SOLUTION: A manufacturing apparatus 10 for a hydraulic cement composition includes a container that enables adding at least one of blast-furnace slag and electric-furnace slag to molten steelmaking slag, allows introducing a gas for component adjustment, and performs tilting so as to discharge a molten mixture serving as a raw material for the hydraulic cement composition.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an apparatus for producing a hydraulic cement composition and a method for producing a hydraulic cement composition. [Background technology]

[0002] Japan's crude steel production volume in 2020 was 83 million tons, of which 62 million tons was produced using the blast furnace method. Assuming that carbon dioxide (CO2) emissions associated with the production of 1 ton of crude steel using the blast furnace method are 2.0 tons, the CO2 emissions from the production of 62 million tons of crude steel would be 124 million tons. This corresponds to 10% of the country's total CO2 emissions, approximately 1.2 billion tons. At the same time, as by-products of crude steel production using the blast furnace method, 20 million tons of blast furnace slag and 9.5 million tons of converter slag were generated in 2020. Various efforts are underway to address these burdens, including the shift from the blast furnace method to the electric furnace method and the development of steelmaking methods with less CO2 emissions. Various efforts are also underway to utilize blast furnace slag and converter slag.

[0003] Blast furnace slag is almost entirely used as a cement raw material, cement admixture, road material, etc. However, it cannot be said that the added value of any of these is sufficiently high, and there is a demand for technologies to utilize it in ways that offer even greater value. There have been attempts to use converter slag in a variety of ways, such as as road material, civil engineering material, fertilizer, and seaweed bed formation material, but compared to blast furnace slag, its development into established uses is limited. There is a demand for technologies to utilize both blast furnace slag and converter slag in ways that offer even greater added value than the current situation.

[0004] Meanwhile, Japan's cement production volume in 2020 was 56 million tons, and assuming CO2 emissions per ton of cement are 0.75 tons, this means that 42 million tons of CO2 were emitted. This is equivalent to approximately 3.5% of the country's total CO2 emissions and roughly one-third of the emissions from steel production, which is a considerable amount of CO2. As a result, various efforts are being made to reduce CO2 emissions associated with cement production.

[0005] Regarding CO2 reduction during cement production, there remains untapped technology for utilizing blast furnace slag and converter slag. Because both blast furnace slag and converter slag are produced in a molten state, if cement compositions could be produced from the molten state, the energy required for current cement production, which involves heating raw materials to 1450°C using a rotary kiln, would be almost unnecessary. Furthermore, because both blast furnace slag and converter slag are already decarbonated materials, there is a possibility that CO2 emissions from the raw materials would be almost zero. In other words, there is the possibility of developing environmentally friendly cement that emits almost no CO2 from energy or raw materials.

[0006] As a technology related to the present invention, for example, in a method for producing hydraulic cement using electric furnace reduced slag produced in a steelmaking process using an electric furnace as an acidic material and quicklime as a basic material, molten electric furnace reduced slag and powdered quicklime are charged into an electric furnace and melted, and nitrogen gas is blown in and mixed to produce a molten mixture, which is then rapidly cooled and solidified to produce hydraulic cement (see Patent Document 1). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent Publication No. 2000-313907 Summary of the Invention [Problem to be solved by the invention]

[0008] However, although the method described in Patent Document 1 is an example that shows that a hydraulic cement composition can be obtained using molten slag, it is a batch-type production method using an electric furnace, and has not yet been adapted for continuous, efficient production.

[0009] As mentioned above, conventional methods use molten slag as a raw material, but the production is carried out in a batch manner using an electric furnace, and it is thought that sufficient production efficiency cannot be achieved.

[0010] The present invention aims to enable the continuous production of a hydraulic cement composition using an acidic material and a basic material as raw materials, with reduced CO2 emitted from the energy required for production and reduced CO2 emitted from the raw materials. [Means for solving the problem]

[0011] The hydraulic cement composition manufacturing apparatus according to the first aspect has a container that can add at least one of blast furnace slag and electric furnace slag to molten steelmaking slag, can introduce gas for adjusting the components, and can be tilted to discharge the molten mixture that serves as a raw material for the hydraulic cement composition. The second aspect includes the steps of: (A) using the hydraulic cement composition manufacturing apparatus according to the first aspect to add at least one of blast furnace slag and electric furnace slag to molten steelmaking slag, and further adding additives as necessary to obtain a molten mixture with adjusted components; (B) cooling and solidifying the molten mixture obtained in (A) to produce clinker; and (C) adding gypsum to the clinker obtained in (B) and pulverizing the clinker.

[0012] In a third aspect, in the method for producing a hydraulic cement composition according to the second aspect, in the step (A), steelmaking slag after metal refining is used as the molten steelmaking slag.

[0013] In a fourth aspect, in the method for producing a hydraulic cement composition according to the second or third aspect, in step (A), carbon is added, oxygen is blown to raise the temperature, and iron oxide in the slag is reduced.

[0014] In a fifth aspect, in the method for producing a hydraulic cement composition according to the second or third aspect, iron oxide in the slag is reduced using carbon monoxide.

[0015] In a sixth aspect, in the method for producing a hydraulic cement composition according to any one of the second to fifth aspects, the steelmaking slag is slag generated by metal refining after removing slag with a high phosphorus concentration in hot metal pretreatment or intermediate slag removal.

[0016] In a seventh aspect, in the method for producing a hydraulic cement composition according to any one of the second to fifth aspects, in step (A), the CaO content is in a range of not less than the value calculated by formula (1) and not more than the value calculated by formula (2), when the total amount of CaO, Al2O3, and SiO2 contained in the molten mixture is taken as 100 mass%. CaO(mass%)=-0.30×Al2O3(mass%)+69...(1) CaO(mass%)=-0.34×Al2O3(mass%)+73...(2) [Effects of the Invention]

[0017] According to the present invention, a hydraulic cement composition can be continuously produced using an acidic material and a basic material as raw materials, with reduced CO2 emitted from the energy required for production and reduced CO2 emitted from the raw materials. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a block diagram showing an apparatus for producing a hydraulic cement composition and a method for producing a hydraulic cement composition according to the present embodiment. FIG. [Figure 2] FIG. 1 is a cross-sectional view showing step (A) using a container. [Figure 3] FIG. 10 is a cross-sectional view showing the state in which the container of the device A is tilted to discharge the molten mixture. [Figure 4] FIG. 10 is a cross-sectional view showing a modified example of step (A). [Figure 5] FIG. 1 is a cross-sectional view showing an example of a method for producing steelmaking slag. [Figure 6] FIG. 1 is a cross-sectional view showing an example of a method for producing steelmaking slag. [Figure 7]FIG. 1 is a cross-sectional view showing an example of a method for producing steelmaking slag. [Figure 8] FIG. 10 is a front view schematically showing device B (step (B)). [Figure 9] FIG. 10 is a front view schematically showing a modified example of the device B (step (B)). DETAILED DESCRIPTION OF THE INVENTION

[0019] In the present disclosure, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits.

[0020] In the numerical ranges described in stages in this disclosure, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, in the numerical ranges described in this disclosure, the upper or lower limit value of that numerical range may be replaced with a value shown in the examples.

[0021] In the drawings of this disclosure, components indicated by the same reference numerals are the same components. The dimensions in the drawings do not necessarily represent the actual dimensions, and may be enlarged or reduced as necessary.

[0022] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In Fig. 1 to Fig. 9, an apparatus 10 for producing a hydraulic cement composition according to this embodiment has an apparatus A. The apparatus 10 for producing a hydraulic cement composition may further have an apparatus B and an apparatus C. The apparatuses A, B, and C correspond to apparatuses for carrying out steps (A), (B), and (C), respectively.

[0023] [Device A] The device A has a container 14 that can be tilted to allow the addition of at least one of blast furnace slag and electric furnace slag to the molten steelmaking slag, that can introduce gas for adjusting the components, and that can discharge the molten mixture 12 that will be used as the raw material for the hydraulic cement composition.

[0024] Blast furnace slag and electric furnace slag are types of acidic materials, and steelmaking slag is a type of basic material. That is, in device A, an acidic material is added to a molten basic material and mixed, and the composition is adjusted with a gas to produce molten mixture 12. The basic material may include converter slag, which is a basic steel slag, or limestone, which is a basic material.

[0025] The vessel 14 is, for example, a converter, and has a furnace throat 14A at its top end and a tap hole 14B on its upper side. Refractory bricks 16 are attached to the inner surface of the vessel 14. An oxygen lance 18 for supplying oxygen gas is inserted from the furnace throat 14A into the interior of the vessel 14. A gas supply pipe 20 is also provided at the bottom of the vessel 14, allowing gas to be supplied into the interior of the vessel 14. The gas supply pipe 20 can supply, for example, oxygen, carbon dioxide, or an inert gas such as nitrogen gas. Nitrogen gas can also enhance the mixing power of the raw materials or the mixing action of the raw materials and the composition adjuster (powder).

[0026] Basic refractory bricks with excellent heat resistance and mechanical properties are desirable for the refractory bricks 16. Chromium-free refractory bricks such as magnesia spinel, magnesia calcium, and magnesia dolomite are suitable. When balancing the basicity and acidity of the refractory bricks 16, it is more desirable to use alumina- or silica-based materials than magnesia-based materials.

[0027] [Device B] 8, apparatus B is an apparatus that continuously quenches the molten mixture 12 obtained from apparatus A to produce clinker 52. As an example, apparatus B is an apparatus that receives granulated material 50 of the molten mixture 12 supplied from apparatus A on a movable mesh panel 48, and while the granulated material 50 is moving, blows air onto the granulated material 50 from multiple points below the mesh panel to quench the granulated material 50 and continuously produce clinker 52, such as an air quenching cooler.

[0028] As shown in Fig. 9, the apparatus B may be configured to include a lower movable mesh 54 that receives the granulated material 50 of the molten mixture 12 from the apparatus A, and an upper movable mesh 56 provided above the lower movable mesh 54. In this configuration, air compressed by a compressor 58 is blown onto the granulated material 50 from multiple points below the lower movable mesh 54 to rapidly cool the granulated material 50 and produce clinker 52. The upper movable mesh 56 prevents the granulated material 50 from separating from the lower movable mesh 54, allowing the clinker 52 to be produced efficiently.

[0029] In the example shown in Figures 8 and 9, the air used in device B may be an air jet or a cold air jet using cooled air.

[0030] [Device C] In Fig. 1, apparatus C is an apparatus for continuously adding gypsum and, for example, a grinding aid to clinker 52 obtained from apparatus B and grinding the clinker 52 to continuously produce a cement composition. Apparatus C may be a ball mill or rod mill having a mechanism for adding gypsum and a grinding aid to clinker 52 (Figs. 8 and 9) supplied from apparatus B, and may be an apparatus for continuously grinding clinker 52.

[0031] Clinker 52 and gypsum are fed to the inlet of device C. Grinding aid may be fed to the inlet side of device C, or to both the inlet and outlet sides. Instead of grinding aid fed to the outlet side, a finishing agent may be fed.

[0032] Gypsum is added to prevent the cement from hardening instantly when it comes into contact with water, ensuring that the fluidity is maintained for construction. Grinding aids coat the surface of the crushed clinker 52 powder and prevent the powder from agglomerating, thereby reducing the crushing time and energy required and making the crushing more efficient. Effective grinding aids include diethylene glycol, triethanolamine, and triisopropanolamine.

[0033] (Method for producing hydraulic cement composition) The method for producing a hydraulic cement composition according to this embodiment includes the following steps: step (A) of adding at least one of blast furnace slag and electric furnace slag to molten steelmaking slag using hydraulic cement composition production apparatus 10, and further adding additives as necessary to obtain a molten mixture 12 with adjusted components; step (B) of cooling and solidifying molten mixture 12 obtained in step (A) to produce clinker; and step (C) of adding gypsum to the clinker obtained in step (B) and pulverizing it.

[0034] The molten mixture 12 obtained in step (A) is discharged, for example, from the furnace throat 14A by tilting the vessel 14, and proceeds to step (B). Steps (B) and (C) are performed using the above-mentioned apparatuses B and C.

[0035] In step (A), steelmaking slag obtained after metal refining may be used as the molten steelmaking slag.

[0036] 4, in step (A), carbon may be added to the vessel 14, and oxygen may be supplied into the vessel 14 from the gas supply pipe 20 to raise the temperature by the heat of oxidation of the carbon and reduce the iron oxide in the slag. Alternatively, carbon monoxide may be supplied as a reducing agent into the vessel 14 from the gas supply pipe 20 to reduce the iron oxide in the slag.

[0037] 5, the molten steelmaking slag may be slag 26 generated by metal refining after removing slag 22 with a high phosphorus concentration. Specifically, the vessel 14 is tilted, and the slag 22 with a high phosphorus concentration is discharged from the slag 26 into another vessel 24, for example, through a tapping port 14B, and the slag 26 remaining in the vessel 14 is used as the molten steelmaking slag in step (A).

[0038] 6, the steelmaking slag may be slag 26 generated by metal refining after removing slag 22 with a high phosphorus concentration during intermediate slag removal in hot metal pretreatment SA or, for example, decarburization treatment SB. Specifically, in hot metal pretreatment SA, the vessel 14 is tilted, and the slag 22 with a high phosphorus concentration is discharged from the slag 26 into another vessel 24 through, for example, the tap hole 14B. Next, the slag 26 remaining in the vessel 14 is transferred to another converter 34, where the decarburization treatment SB is performed. In the intermediate slag removal in this decarburization treatment SB, the converter 34 is tilted, and the slag 22 with a high phosphorus concentration is discharged into another vessel 36, and the slag 26 remaining in the converter 34 may be used as the molten steelmaking slag in step (A).

[0039] Furthermore, as shown in FIG. 7, metal refining may be performed using one vessel 14, and slag 22 with a high phosphorus concentration may be removed as intermediate slag, and the slag 26 remaining in the vessel 14 may be used as molten steelmaking slag in step (A).

[0040] In step (A), the CaO content is in a range equal to or greater than the value calculated by formula (1) and equal to or less than the value calculated by formula (2) when the total amount of CaO, Al2O3, and SiO2 contained in the molten mixture 12 is taken as 100 mass%.

[0041] CaO(mass%)=-0.30×Al2O3(mass%)+69...(1) CaO(mass%)=-0.34×Al2O3(mass%)+73...(2)

[0042] As described above, according to this embodiment, a hydraulic cement composition can be continuously produced using an acidic material and a basic material as raw materials, with reduced CO2 emitted from the energy required for production and reduced CO2 emitted from the raw materials. This makes it possible to provide an improved hydraulic cement composition production device.

[0043] [Other embodiments] The above describes one example of an embodiment of the present invention, but the embodiment of the present invention is not limited to the above, and it goes without saying that various modifications can be made without departing from the spirit of the present invention. [Explanation of symbols]

[0044] 10 Hydraulic cement composition manufacturing apparatus 12 Molten mixture 14 Container 52 Clinker SA Hot Metal Pretreatment

Claims

1. An apparatus for producing a hydraulic cement composition, which has a container that can add at least one of blast furnace slag and electric furnace slag to molten steelmaking slag, can introduce gas for adjusting the components, and can be tilted to discharge the molten mixture that is the raw material for the hydraulic cement composition.

2. A step (A) of adding at least one of blast furnace slag and electric furnace slag to molten steelmaking slag using the hydraulic cement composition manufacturing apparatus according to claim 1, and further adding additives as necessary to obtain a molten mixture having adjusted components; Step (B) of cooling and solidifying the molten mixture obtained in step (A) to produce clinker; Step (C) of adding gypsum to the clinker obtained in step (B) and pulverizing it; A method for producing a hydraulic cement composition comprising:

3. 3. The method for producing a hydraulic cement composition according to claim 2, wherein in step (A), steelmaking slag obtained after metal refining is used as the molten steelmaking slag.

4. 3. The method for producing a hydraulic cement composition according to claim 2, wherein in step (A), carbon is added, oxygen is blown to raise the temperature, and iron oxide in the slag is reduced.

5. 3. The method for producing a hydraulic cement composition according to claim 2, wherein the iron oxide in the slag is reduced using carbon monoxide.

6. 3. The method for producing a hydraulic cement composition according to claim 2, wherein the steelmaking slag is slag generated by metal refining after removing slag with a high phosphorus concentration from molten iron pretreatment or intermediate slag removal.

7. In the step (A), the content of CaO is ２ O ３ , and SiO ２ The method for producing a hydraulic cement composition according to any one of claims 2 to 5, wherein the value calculated by formula (1) is equal to or greater than the value calculated by formula (2) when the total amount of the above is taken as 100 mass%. CaO (mass%) = -0.30 × Al ２ O ３ (mass%) +69 ・・・(1) CaO (mass%) = -0.34 × Al ２ O ３ (mass%) +73 ・・・(2)

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